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Deep ocean currents in Antarctica are slowing

GS Paper 1

 Syllabus: Geography: Ocean Current


Source: TH

 Context: The deep ocean currents (called ‘Overturning Circulations’) in Antarctica, which play a crucial role in redistributing heat, carbon, and nutrients around the globe, are slowing down earlier than predicted (as per the new research, published in the journal Nature Climate Change)



  • Overturning circulation has slowed by almost a third (30%) and deep ocean oxygen levels are declining.
  • These changes were expected by 2050, but are already happening


What are the Overturning Circulations?

Overturning Circulations refers to the global network of ocean currents that redistribute heat, carbon, and nutrients. They play a crucial role in regulating Earth’s climate, maintaining oxygen levels, and shaping ocean currents.


Why are the Overturning Circulations slowing?

The Overturning Circulations are slowing due to melting Antarctic ice, which freshens surface waters and reduces their density, hindering the sinking process and disrupting the circulation pattern.


Impact of ‘the Slowing’:

  • It can lead to reduced oxygen levels in the deep ocean, affecting marine organisms.
  • Disrupts the base of the food chain:As the Southern Ocean supports about three-quarters of global phytoplankton production → impacts the marine ecosystem.
  • It can also intensify global warming by reducing the ocean’s capacity to store carbon dioxide and heat.
  • It can contribute to rising sea levels due to the thermal expansion of warmer waters.


About Deep Water Circulations (DWC):

Deep Water Circulation (DWC)
AboutDWC refers to the movement of water in the deep ocean, driven by density differences caused by temperature and salinity variations.
FormationIn polar regions, sea ice formation causes surrounding seawater to become saltier and denser, leading to sinking. The process repeats as surface water is pulled in to replace sinking water. This circulation pattern is known as thermohaline circulation.
SignificanceHeat Distribution; Carbon Dioxide Control; Shapes ocean currents and circulation patterns globally;  Affects sea level by redistributing heat and influencing thermal expansion
Deep-Water Circulations in the Indian OceanThe Indian Ocean does not produce its own deep water; it receives it from other sources like the North Atlantic and the Antarctic.


Insta Links:


Prelims Links: (UPSC 2021)

Consider the following statements:

  1. In the tropical zone, the western sections of the oceans are warmer than the eastern sections owing to the influence of trade winds.
  2. In the temperate Zone, westerlies make the eastern sections of oceans warmer than the western sections


Which of the statements given above is/are correct?

  1. 1 only
  2. 2 only
  3. Both 1 and 2
  4. Neither 1 and 2


Ans: 3